ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



249 



It consists of two parts, the glass apparatus for dehydrating and a metal 

 frame, which is in connection with a motor apparatus. The latter 

 imparts an oscillating movement to the dehydrator, so that currents are 

 set up whereby the fluids become more rapidly and intimately mixed. 

 The motor apparatus can also be used as a shaker for decalcitication, for 

 emulsifying, for photographic work, or for driving a microtome. 



The' dehydrator proper (fig. 48) consists of an upper bulbous glass 

 receptacle, terminating below in a tube, the extremity of which dips 

 into a glass reservoir intended for the reception of the sections and 

 specimens to be dehydrated. The bulb is closed above by a glass stopper, 

 with a bore for the purpose of admitting air, and for regulating the 

 pressure inside the bulb. The reservoir is supplied with a doubly bent 

 syphon for carrying off superfluous fluid 

 into the lowermost receptacle. The neck 

 of the tube from the bulb is stuffed with 

 dry copper-sulphate and also with cotton 

 or glass wool. 



Apparatus for Washing" Sections.* — 

 A. Frazer has devised an apparatus which 

 consists of a shallow metal trough about 

 3 in. deep and 4 in. square. Within it 

 are placed four wide test-tubes, into the 

 lower parts of which a number of small 

 holes are made. The trough is furnished 

 with several wires placed crosswise : these 

 keep the test tubes apart and in a vertical 

 position. The various sections to be 

 washed are placed in the tubes, and water 

 is allowed to circulate in the trough. The 

 holes in the tubes are large enough to allow 

 the water to circulate freely, but small 

 enough to prevent the sections from passing 

 out. The apparatus can, of course, be con- 

 structed to contain any number of tubes. 



Aceton in Microscopical Technique. f—Gr. Marpmann describes 

 some of the properties of acetx)n and its uses in microscopical technique. 

 It is miscible with water, alcohol, and other fluids, and a good solvent of 

 most substances except proteids. It can be used as a preservative for 

 animal and vegetable specimens. A mixture of 1 part of aceton and 

 9 parts of water is extremely serviceable for keeping green or blue algfe. 

 For animal preparations, aceton 1 part, glycerin ;> parts, and water 

 6 parts, is recommended. As a fixative, aceton 50 parts, water 50 parts, 

 sublimate 1 part, may be used. In this mixture the preparations remain 

 for two or more days according to size, and are afterwards transferred to 

 pure aceton, repeatedly changed. They are then imliedded in celluloid 

 solution or in a solution of pyroxylin 1 part, camphor 1 part, aceton 

 8 parts. This medium is quite as suitable for section purposes as 

 celloidin. 



Fig. 48. 



* Proc. Scot. Micr. Soc, iv. (1906) p. 68. 



t Zeitschr. angew. Mikrosk., xii. (1906) pp. 157-61. 



